Bidirectional bipolar junction transistor devices from bonded wide and thick wafers

EP4631104A1Inactive Publication Date: 2025-10-15IDEAL POWER INC
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Patent Information

Application Number
EP2023825569
Authority / Receiving Office
EP · EP
Patent Type
Applications
Current Assignee / Owner
Priority Date
2022-12-08
Filing Date
2023-11-17
Publication Date
2025-10-15
Estimated Expiration
Not applicable · inactive patent

AI Technical Summary

Technical Problem

Bidirectional bipolar junction transistors (BJTs) experience a significant collector-emitter voltage drop during current flow, leading to power loss, which is challenging to reduce in large volume production using thin semiconductor wafers due to increased risk of breakage and thickness constraints.

Method used

The method involves fabricating thin bidirectional BJT devices by bonding two thick semiconductor wafers together after grinding them into thin wafers, with different conductivity-type dopants activated using diffusion and laser anneal processes to form base and emitter/collector regions on both sides, allowing for closer positioning of collector-emitters and reducing the overall thickness.

Benefits of technology

This approach decreases the collector-emitter voltage drop by approximately 30% while enabling high-volume production on larger wafers, reducing the risk of breakage and maintaining high-quality drift regions with lower costs.

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Abstract

Thin bidirectional bipolar junction transistor (BJT, B-TRAN) devices and methods for fabricating thin bidirectional BJT devices. The method includes first forming a first base region (108) and a first emitter / collector region (110) on a first side of a first thick semiconductor wafer. The method includes as a next step removing a portion of the first thick semiconductor wafer to produce a first thin semiconductor wafer (106). The method then includes as a next step forming a second base region (112) and a second emitter / collector region (114) on a second side of the first thin semiconductor wafer (106) opposite the first side. In the same way a second thin semiconductor wafer (128) is formed with respective base (130, 134) and collector / emitter (132, 136) regions. The method further includes bonding the first thin semiconductor wafer (106) to the second thin semiconductor wafer (128), where facing base and emitter / collector regions are bonded together such that they are electrically connected.
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